This invention relates to automatic control apparatus for an air conditioning system and more specifically to such apparatus adapted to provide energy saving modes of operation during at least two different time periods in a 24 hour period. The present invention is particularly adapted for use with a heat pump air conditioning system capable of providing both heating and cooling operating modes to maintain a desired normal comfort level within the conditioned space.
It is well known in heating and cooling systems to provide control apparatus which will automatically adjust the system set point temperature during a portion of the day so as to use less energy than would be required to hold the conditioned space temperature at a normal or customary comfort level. For example, controls are commonly available that can be set to cause the set point temperature of a heating system to be set back to a lower temperature, either at night while the occupants of a residence are asleep or during the daylight hours while the occupants are away at work. Additionally, there is at least one control available that also permits temperature set back during two separate time periods in the day so as to cover both periods of absence. With this latter control the set back temperature is the same for both time periods.
It is, therefore, an object of the present invention to provide automatic control apparatus for an air conditioning system which will establish for two different time periods independent temperature settings which can be different for each time period thus permitting independent selection of the desired energy saving modes of operation.
It is a further object of the present invention to provide control apparatus particularly useful with a heat pump type of air conditioning system which will automatically raise or lower the set point temperature from the normal set temperature to independently selected different temperature settings for two different time periods of the day thus selectively providing, for example, different levels of energy saving modes of operation by day and night time periods.
It is a still further object of the present invention to provide control apparatus of the type described which will establish two energy saving modes of operation with respectively different setpoint temperatures during two different time periods of the day which time periods may have overlapping time segments wherein the control apparatus is adapted to select the most energy efficient mode of operation as determined by the respective set point temperatures for each of the overlapping time segments.
It is yet a further object of the present invention to provide control apparatus of the type described which will establish energy saving set point temperatures different from the normal temperature setting and which will automatically assure that at least a predetermined minimum differential in the energy saving direction is maintained between the normal and energy saving set point temperatures when a change in the normal temperature setting occurs.